I believe that you are in a little bit error…
Those 0x20, 0x5b, 0x58… that you name them “Section Type” are in fact the 8 bit checksum of the 0x49 bytes block preceding.
See below what I mean… Blue - block len, Green - data, Red - 8 bit checksum of the current block of data.
And so on… up until the end of file.
